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VMware vSphere infrastructure requirements

You must install the OKD cluster on a VMware vSphere version 7.0 Update 2 or later instance that meets the requirements for the components that you use.

OKD version 4 supports VMware vSphere version 8.0.

You can host the VMware vSphere infrastructure on-premise or on a VMware Cloud Verified provider that meets the requirements outlined in the following tables:

Table 1. Version requirements for vSphere virtual environments
Virtual environment product Required version

VMware virtual hardware

15 or later

vSphere ESXi hosts

7.0 Update 2 or later

vCenter host

7.0 Update 2 or later

You must ensure that the time on your ESXi hosts is synchronized before you install OKD. See Edit Time Configuration for a Host in the VMware documentation.

Table 2. Minimum supported vSphere version for VMware components
Component Minimum supported versions Description

Hypervisor

vSphere 7.0 Update 2 and later with virtual hardware version 15

This version is the minimum version that Fedora CoreOS (FCOS) supports. For more information about supported hardware on the latest version of Fedora that is compatible with FCOS, see Hardware on the Red Hat Customer Portal.

Storage with in-tree drivers

vSphere 7.0 Update 2 and later

This plugin creates vSphere storage by using the in-tree storage drivers for vSphere included in OKD.

Optional: Networking (NSX-T)

vSphere 7.0 Update 2 and later

vSphere 7.0 Update 2 is required for OKD. For more information about the compatibility of NSX and OKD, see the Release Notes section of VMware’s NSX container plugin documentation.

To ensure the best performance conditions for your cluster workloads that operate on Oracle® Cloud Infrastructure (OCI) and on the Oracle® Cloud VMware Solution (OCVS) service, ensure volume performance units (VPUs) for your block volume are sized for your workloads.

The following list provides some guidance in selecting the VPUs needed for specific performance needs:

  • Test or proof of concept environment: 100 GB, and 20 to 30 VPUs.

  • Base-production environment: 500 GB, and 60 VPUs.

  • Heavy-use production environment: More than 500 GB, and 100 or more VPUs.

Consider allocating additional VPUs to give enough capacity for updates and scaling activities. See Block Volume Performance Levels in the Oracle documentation.

VMware vSphere CSI Driver Operator requirements

To install the vSphere Container Storage Interface (CSI) Driver Operator, the following requirements must be met:

  • VMware vSphere version 7.0 Update 2 or later

  • vCenter 7.0 Update 2 or later

  • Virtual machines of hardware version 15 or later

  • No third-party vSphere CSI driver already installed in the cluster

If a third-party vSphere CSI driver is present in the cluster, OKD does not overwrite it. The presence of a third-party vSphere CSI driver prevents OKD from updating to OKD 4.13 or later.

The VMware vSphere CSI Driver Operator is supported only on clusters deployed with platform: vsphere in the installation manifest.

You can create a custom role for the Container Storage Interface (CSI) driver, the vSphere CSI Driver Operator, and the vSphere Problem Detector Operator. The custom role can include privilege sets that assign a minimum set of permissions to each vSphere object. This means that the CSI driver, the vSphere CSI Driver Operator, and the vSphere Problem Detector Operator can establish a basic interaction with these objects.

Installing an OKD cluster in a vCenter is tested against a full list of privileges as described in the "Required vCenter account privileges" section. By adhering to the full list of privileges, you can reduce the possibility of unexpected and unsupported behaviors that might occur when creating a custom role with a set of restricted privileges.

Additional resources

Requirements for a cluster with user-provisioned infrastructure

For a cluster that contains user-provisioned infrastructure, you must deploy all of the required machines.

This section describes the requirements for deploying OKD on user-provisioned infrastructure.

vCenter requirements

Before you install an OKD cluster on your vCenter that uses infrastructure that you provided, you must prepare your environment.

Required vCenter account privileges

To install an OKD cluster in a vCenter, your vSphere account must include privileges for reading and creating the required resources. Using an account that has global administrative privileges is the simplest way to access all of the necessary permissions.

Roles and privileges required for installation in vSphere API
vSphere object for role When required Required privileges in vSphere API

vSphere vCenter

Always

Cns.Searchable
InventoryService.Tagging.AttachTag
InventoryService.Tagging.CreateCategory
InventoryService.Tagging.CreateTag
InventoryService.Tagging.DeleteCategory
InventoryService.Tagging.DeleteTag
InventoryService.Tagging.EditCategory
InventoryService.Tagging.EditTag
Sessions.ValidateSession
StorageProfile.Update
StorageProfile.View

vSphere vCenter Cluster

If VMs will be created in the cluster root

Host.Config.Storage
Resource.AssignVMToPool
VApp.AssignResourcePool
VApp.Import
VirtualMachine.Config.AddNewDisk

vSphere vCenter Resource Pool

If an existing resource pool is provided

Resource.AssignVMToPool
VApp.AssignResourcePool
VApp.Import
VirtualMachine.Config.AddNewDisk

vSphere Datastore

Always

Datastore.AllocateSpace
Datastore.Browse
Datastore.FileManagement
InventoryService.Tagging.ObjectAttachable

vSphere Port Group

Always

Network.Assign

Virtual Machine Folder

Always

InventoryService.Tagging.ObjectAttachable
Resource.AssignVMToPool
VApp.Import
VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddNewDisk
VirtualMachine.Config.AddRemoveDevice
VirtualMachine.Config.AdvancedConfig
VirtualMachine.Config.Annotation
VirtualMachine.Config.CPUCount
VirtualMachine.Config.DiskExtend
VirtualMachine.Config.DiskLease
VirtualMachine.Config.EditDevice
VirtualMachine.Config.Memory
VirtualMachine.Config.RemoveDisk
VirtualMachine.Config.Rename
Host.Config.Storage
VirtualMachine.Config.ResetGuestInfo
VirtualMachine.Config.Resource
VirtualMachine.Config.Settings
VirtualMachine.Config.UpgradeVirtualHardware
VirtualMachine.Interact.GuestControl
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Interact.Reset
VirtualMachine.Inventory.Create
VirtualMachine.Inventory.CreateFromExisting
VirtualMachine.Inventory.Delete
VirtualMachine.Provisioning.Clone
VirtualMachine.Provisioning.MarkAsTemplate
VirtualMachine.Provisioning.DeployTemplate

vSphere vCenter Datacenter

If the installation program creates the virtual machine folder. For user-provisioned infrastructure, VirtualMachine.Inventory.Create and VirtualMachine.Inventory.Delete privileges are optional if your cluster does not use the Machine API. See the "Minimum permissions for the Machine API" table.

InventoryService.Tagging.ObjectAttachable
Resource.AssignVMToPool
VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddNewDisk
VirtualMachine.Config.AddRemoveDevice
VirtualMachine.Config.AdvancedConfig
VirtualMachine.Config.Annotation
VirtualMachine.Config.CPUCount
VirtualMachine.Config.DiskExtend
VirtualMachine.Config.DiskLease
VirtualMachine.Config.EditDevice
VirtualMachine.Config.Memory
VirtualMachine.Config.RemoveDisk
VirtualMachine.Config.Rename
VirtualMachine.Config.ResetGuestInfo
VirtualMachine.Config.Resource
VirtualMachine.Config.Settings
VirtualMachine.Config.UpgradeVirtualHardware
VirtualMachine.Interact.GuestControl
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Interact.Reset
VirtualMachine.Inventory.Create
VirtualMachine.Inventory.CreateFromExisting
VirtualMachine.Inventory.Delete
VirtualMachine.Provisioning.Clone
VirtualMachine.Provisioning.DeployTemplate
VirtualMachine.Provisioning.MarkAsTemplate
Folder.Create
Folder.Delete

Roles and privileges required for installation in vCenter graphical user interface (GUI)
vSphere object for role When required Required privileges in vCenter GUI

vSphere vCenter

Always

Cns.Searchable
"vSphere Tagging"."Assign or Unassign vSphere Tag"
"vSphere Tagging"."Create vSphere Tag Category"
"vSphere Tagging"."Create vSphere Tag"
vSphere Tagging"."Delete vSphere Tag Category"
"vSphere Tagging"."Delete vSphere Tag"
"vSphere Tagging"."Edit vSphere Tag Category"
"vSphere Tagging"."Edit vSphere Tag"
Sessions."Validate session"
"Profile-driven storage"."Profile-driven storage update"
"Profile-driven storage"."Profile-driven storage view"

vSphere vCenter Cluster

If VMs will be created in the cluster root

Host.Configuration."Storage partition configuration"
Resource."Assign virtual machine to resource pool"
VApp."Assign resource pool"
VApp.Import
"Virtual machine"."Change Configuration"."Add new disk"

vSphere vCenter Resource Pool

If an existing resource pool is provided

Host.Configuration."Storage partition configuration"
Resource."Assign virtual machine to resource pool"
VApp."Assign resource pool"
VApp.Import
"Virtual machine"."Change Configuration"."Add new disk"

vSphere Datastore

Always

Datastore."Allocate space"
Datastore."Browse datastore"
Datastore."Low level file operations"
"vSphere Tagging"."Assign or Unassign vSphere Tag on Object"

vSphere Port Group

Always

Network."Assign network"

Virtual Machine Folder

Always

"vSphere Tagging"."Assign or Unassign vSphere Tag on Object"
Resource."Assign virtual machine to resource pool"
VApp.Import
"Virtual machine"."Change Configuration"."Add existing disk"
"Virtual machine"."Change Configuration"."Add new disk"
"Virtual machine"."Change Configuration"."Add or remove device"
"Virtual machine"."Change Configuration"."Advanced configuration"
"Virtual machine"."Change Configuration"."Set annotation"
"Virtual machine"."Change Configuration"."Change CPU count"
"Virtual machine"."Change Configuration"."Extend virtual disk"
"Virtual machine"."Change Configuration"."Acquire disk lease"
"Virtual machine"."Change Configuration"."Modify device settings"
"Virtual machine"."Change Configuration"."Change Memory"
"Virtual machine"."Change Configuration"."Remove disk"
"Virtual machine"."Change Configuration".Rename
"Virtual machine"."Change Configuration"."Reset guest information"
"Virtual machine"."Change Configuration"."Change resource"
"Virtual machine"."Change Configuration"."Change Settings"
"Virtual machine"."Change Configuration"."Upgrade virtual machine compatibility"
"Virtual machine".Interaction."Guest operating system management by VIX API"
"Virtual machine".Interaction."Power off"
"Virtual machine".Interaction."Power on"
"Virtual machine".Interaction.Reset
"Virtual machine"."Edit Inventory"."Create new"
"Virtual machine"."Edit Inventory"."Create from existing"
"Virtual machine"."Edit Inventory"."Remove"
"Virtual machine".Provisioning."Clone virtual machine"
"Virtual machine".Provisioning."Mark as template"
"Virtual machine".Provisioning."Deploy template"

vSphere vCenter Datacenter

If the installation program creates the virtual machine folder. For user-provisioned infrastructure, VirtualMachine.Inventory.Create and VirtualMachine.Inventory.Delete privileges are optional if your cluster does not use the Machine API.

"vSphere Tagging"."Assign or Unassign vSphere Tag on Object"
Resource."Assign virtual machine to resource pool"
VApp.Import
"Virtual machine"."Change Configuration"."Add existing disk"
"Virtual machine"."Change Configuration"."Add new disk"
"Virtual machine"."Change Configuration"."Add or remove device"
"Virtual machine"."Change Configuration"."Advanced configuration"
"Virtual machine"."Change Configuration"."Set annotation"
"Virtual machine"."Change Configuration"."Change CPU count"
"Virtual machine"."Change Configuration"."Extend virtual disk"
"Virtual machine"."Change Configuration"."Acquire disk lease"
"Virtual machine"."Change Configuration"."Modify device settings"
"Virtual machine"."Change Configuration"."Change Memory"
"Virtual machine"."Change Configuration"."Remove disk"
"Virtual machine"."Change Configuration".Rename
"Virtual machine"."Change Configuration"."Reset guest information"
"Virtual machine"."Change Configuration"."Change resource"
"Virtual machine"."Change Configuration"."Change Settings"
"Virtual machine"."Change Configuration"."Upgrade virtual machine compatibility"
"Virtual machine".Interaction."Guest operating system management by VIX API"
"Virtual machine".Interaction."Power off"
"Virtual machine".Interaction."Power on"
"Virtual machine".Interaction.Reset
"Virtual machine"."Edit Inventory"."Create new"
"Virtual machine"."Edit Inventory"."Create from existing"
"Virtual machine"."Edit Inventory"."Remove"
"Virtual machine".Provisioning."Clone virtual machine"
"Virtual machine".Provisioning."Deploy template"
"Virtual machine".Provisioning."Mark as template"
Folder."Create folder"
Folder."Delete folder"

Additionally, the user requires some ReadOnly permissions, and some of the roles require permission to propogate the permissions to child objects. These settings vary depending on whether or not you install the cluster into an existing folder.

Required permissions and propagation settings
vSphere object When required Propagate to children Permissions required

vSphere vCenter

Always

False

Listed required privileges

vSphere vCenter Datacenter

Existing folder

False

ReadOnly permission

Installation program creates the folder

True

Listed required privileges

vSphere vCenter Cluster

Existing resource pool

False

ReadOnly permission

VMs in cluster root

True

Listed required privileges

vSphere vCenter Datastore

Always

False

Listed required privileges

vSphere Switch

Always

False

ReadOnly permission

vSphere Port Group

Always

False

Listed required privileges

vSphere vCenter Virtual Machine Folder

Existing folder

True

Listed required privileges

vSphere vCenter Resource Pool

Existing resource pool

True

Listed required privileges

For more information about creating an account with only the required privileges, see vSphere Permissions and User Management Tasks in the vSphere documentation.

Minimum required vCenter account privileges

After you create a custom role and assign privileges to it, you can create permissions by selecting specific vSphere objects and then assigning the custom role to a user or group for each object.

Before you create permissions or request for the creation of permissions for a vSphere object, determine what minimum permissions apply to the vSphere object. By doing this task, you can ensure a basic interaction exists between a vSphere object and OKD architecture.

If you create a custom role and you do not assign privileges to it, the vSphere Server by default assigns a Read Only role to the custom role. Note that for the cloud provider API, the custom role only needs to inherit the privileges of the Read Only role.

Consider creating a custom role when an account with global administrative privileges does not meet your needs.

Accounts that are not configured with the required privileges are unsupported. Installing an OKD cluster in a vCenter is tested against a full list of privileges as described in the "Required vCenter account privileges" section. By adhering to the full list of privileges, you can reduce the possibility of unexpected behaviors that might occur when creating a custom role with a restricted set of privileges.

The following tables list the minimum permissions for a vSphere object that interacts with specific OKD architecture. VApp.Import

Minimum permissions for post-installation management of components
vSphere object for role When required Required privileges

vSphere vCenter

Always

Cns.Searchable
InventoryService.Tagging.AttachTag
InventoryService.Tagging.CreateCategory
InventoryService.Tagging.CreateTag
InventoryService.Tagging.DeleteCategory
InventoryService.Tagging.DeleteTag
InventoryService.Tagging.EditCategory
InventoryService.Tagging.EditTag
Sessions.ValidateSession
StorageProfile.Update
StorageProfile.View

vSphere vCenter Cluster

If you intend to create VMs in the cluster root

Host.Config.Storage
Resource.AssignVMToPool

vSphere vCenter Resource Pool

If you provide an existing resource pool in the install-config.yaml file

Host.Config.Storage

vSphere Datastore

Always

Datastore.AllocateSpace
Datastore.Browse
Datastore.FileManagement
InventoryService.Tagging.ObjectAttachable

vSphere Port Group

Always

Network.Assign

Virtual Machine Folder

Always

VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddRemoveDevice
VirtualMachine.Config.AdvancedConfig
VirtualMachine.Config.Annotation
VirtualMachine.Config.CPUCount
VirtualMachine.Config.DiskExtend
VirtualMachine.Config.Memory
VirtualMachine.Config.Settings
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Inventory.CreateFromExisting
VirtualMachine.Inventory.Delete
VirtualMachine.Provisioning.Clone
VirtualMachine.Provisioning.DeployTemplate

vSphere vCenter Datacenter

If the installation program creates the virtual machine folder. For user-provisioned infrastructure, VirtualMachine.Inventory.Create and VirtualMachine.Inventory.Delete privileges are optional if your cluster does not use the Machine API. If your cluster does use the Machine API and you want to set the minimum set of permissions for the API, see the "Minimum permissions for the Machine API" table.

Resource.AssignVMToPool
VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddRemoveDevice
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Provisioning.DeployTemplate

Minimum permissions for the storage components
vSphere object for role When required Required privileges

vSphere vCenter

Always

Cns.Searchable
InventoryService.Tagging.CreateCategory
InventoryService.Tagging.CreateTag
InventoryService.Tagging.EditCategory
InventoryService.Tagging.EditTag
StorageProfile.Update
StorageProfile.View

vSphere vCenter Cluster

If you intend to create VMs in the cluster root

Host.Config.Storage

vSphere vCenter Resource Pool

If you provide an existing resource pool in the install-config.yaml file

Host.Config.Storage

vSphere Datastore

Always

Datastore.Browse
Datastore.FileManagement
InventoryService.Tagging.ObjectAttachable

vSphere Port Group

Always

Read Only

Virtual Machine Folder

Always

VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddRemoveDevice

vSphere vCenter Datacenter

If the installation program creates the virtual machine folder. For user-provisioned infrastructure, VirtualMachine.Inventory.Create and VirtualMachine.Inventory.Delete privileges are optional if your cluster does not use the Machine API. If your cluster does use the Machine API and you want to set the minimum set of permissions for the API, see the "Minimum permissions for the Machine API" table.

VirtualMachine.Config.AddExistingDisk
VirtualMachine.Config.AddRemoveDevice

Minimum permissions for the Machine API
vSphere object for role When required Required privileges

vSphere vCenter

Always

InventoryService.Tagging.AttachTag
InventoryService.Tagging.CreateCategory
InventoryService.Tagging.CreateTag
InventoryService.Tagging.DeleteCategory
InventoryService.Tagging.DeleteTag
InventoryService.Tagging.EditCategory
InventoryService.Tagging.EditTag
Sessions.ValidateSession
StorageProfile.Update
StorageProfile.View

vSphere vCenter Cluster

If you intend to create VMs in the cluster root

Resource.AssignVMToPool

vSphere vCenter Resource Pool

If you provide an existing resource pool in the install-config.yaml file

Read Only

vSphere Datastore

Always

Datastore.AllocateSpace
Datastore.Browse

vSphere Port Group

Always

Network.Assign

Virtual Machine Folder

Always

VirtualMachine.Config.AddRemoveDevice
VirtualMachine.Config.AdvancedConfig
VirtualMachine.Config.Annotation
VirtualMachine.Config.CPUCount
VirtualMachine.Config.DiskExtend
VirtualMachine.Config.Memory
VirtualMachine.Config.Settings
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Inventory.CreateFromExisting
VirtualMachine.Inventory.Delete
VirtualMachine.Provisioning.Clone
VirtualMachine.Provisioning.DeployTemplate

vSphere vCenter Datacenter

If the installation program creates the virtual machine folder. For user-provisioned infrastructure, VirtualMachine.Inventory.Create and VirtualMachine.Inventory.Delete privileges are optional if your cluster does not use the Machine API.

Resource.AssignVMToPool
VirtualMachine.Interact.PowerOff
VirtualMachine.Interact.PowerOn
VirtualMachine.Provisioning.DeployTemplate

Using OKD with vMotion

If you intend on using vMotion in your vSphere environment, consider the following before installing an OKD cluster.

  • OKD generally supports compute-only vMotion, where generally implies that you meet all VMware best practices for vMotion.

    To help ensure the uptime of your compute and control plane nodes, ensure that you follow the VMware best practices for vMotion, and use VMware anti-affinity rules to improve the availability of OKD during maintenance or hardware issues.

    For more information about vMotion and anti-affinity rules, see the VMware vSphere documentation for vMotion networking requirements and VM anti-affinity rules.

  • Using Storage vMotion can cause issues and is not supported. If you are using vSphere volumes in your pods, migrating a VM across datastores, either manually or through Storage vMotion, causes invalid references within OKD persistent volume (PV) objects that can result in data loss.

  • OKD does not support selective migration of VMDKs across datastores, using datastore clusters for VM provisioning or for dynamic or static provisioning of PVs, or using a datastore that is part of a datastore cluster for dynamic or static provisioning of PVs.

    You can specify the path of any datastore that exists in a datastore cluster. By default, Storage Distributed Resource Scheduler (SDRS), which uses Storage vMotion, is automatically enabled for a datastore cluster. Red Hat does not support Storage vMotion, so you must disable Storage DRS to avoid data loss issues for your OKD cluster.

    If you must specify VMs across multiple datastores, use a datastore object to specify a failure domain in your cluster’s install-config.yaml configuration file. For more information, see "VMware vSphere region and zone enablement".

Cluster resources

When you deploy an OKD cluster that uses infrastructure that you provided, you must create the following resources in your vCenter instance:

  • 1 Folder

  • 1 Tag category

  • 1 Tag

  • Virtual machines:

    • 1 template

    • 1 temporary bootstrap node

    • 3 control plane nodes

    • 3 compute machines

Although these resources use 856 GB of storage, the bootstrap node is destroyed during the cluster installation process. A minimum of 800 GB of storage is required to use a standard cluster.

If you deploy more compute machines, the OKD cluster will use more storage.

Cluster limits

Available resources vary between clusters. The number of possible clusters within a vCenter is limited primarily by available storage space and any limitations on the number of required resources. Be sure to consider both limitations to the vCenter resources that the cluster creates and the resources that you require to deploy a cluster, such as IP addresses and networks.

Networking requirements

Use Dynamic Host Configuration Protocol (DHCP) for the network and ensure that the DHCP server is configured to provide persistent IP addresses to the cluster machines.

You do not need to use the DHCP for the network if you want to provision nodes with static IP addresses.

Configure the default gateway to use the DHCP server. All nodes must be in the same VLAN. You cannot scale the cluster using a second VLAN as a Day 2 operation.

You must use the Dynamic Host Configuration Protocol (DHCP) for the network and ensure that the DHCP server is configured to provide persistent IP addresses to the cluster machines. In the DHCP lease, you must configure the DHCP to use the default gateway. All nodes must be in the same VLAN. You cannot scale the cluster using a second VLAN as a Day 2 operation.

If you are installing to a restricted environment, the VM in your restricted network must have access to vCenter so that it can provision and manage nodes, persistent volume claims (PVCs), and other resources.

Additionally, you must create the following networking resources before you install the OKD cluster:

It is recommended that each OKD node in the cluster must have access to a Network Time Protocol (NTP) server that is discoverable via DHCP. Installation is possible without an NTP server. However, asynchronous server clocks will cause errors, which NTP server prevents.

DNS records

You must create DNS records for two static IP addresses in the appropriate DNS server for the vCenter instance that hosts your OKD cluster. In each record, <cluster_name> is the cluster name and <base_domain> is the cluster base domain that you specify when you install the cluster. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Table 3. Required DNS records
Component Record Description

API VIP

api.<cluster_name>.<base_domain>.

This DNS A/AAAA or CNAME (Canonical Name) record must point to the load balancer for the control plane machines. This record must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

Ingress VIP

*.apps.<cluster_name>.<base_domain>.

A wildcard DNS A/AAAA or CNAME record that points to the load balancer that targets the machines that run the Ingress router pods, which are the worker nodes by default. This record must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

Required machines for cluster installation

The smallest OKD clusters require the following hosts:

Table 4. Minimum required hosts
Hosts Description

One temporary bootstrap machine

The cluster requires the bootstrap machine to deploy the OKD cluster on the three control plane machines. You can remove the bootstrap machine after you install the cluster.

Three control plane machines

The control plane machines run the Kubernetes and OKD services that form the control plane.

At least two compute machines, which are also known as worker machines.

The workloads requested by OKD users run on the compute machines.

To maintain high availability of your cluster, use separate physical hosts for these cluster machines.

The bootstrap and control plane machines must use Fedora CoreOS (FCOS) as the operating system. However, the compute machines can choose between Fedora CoreOS (FCOS), Fedora 8.6 and later.

Minimum resource requirements for cluster installation

Each cluster machine must meet the following minimum requirements:

Table 5. Minimum resource requirements
Machine Operating System vCPU Virtual RAM Storage Input/Output Per Second (IOPS)[1]

Bootstrap

FCOS

4

16 GB

100 GB

300

Control plane

FCOS

4

16 GB

100 GB

300

Compute

FCOS

2

8 GB

100 GB

300

  1. OKD and Kubernetes are sensitive to disk performance, and faster storage is recommended, particularly for etcd on the control plane nodes which require a 10 ms p99 fsync duration. Note that on many cloud platforms, storage size and IOPS scale together, so you might need to over-allocate storage volume to obtain sufficient performance.

  2. As with all user-provisioned installations, if you choose to use Fedora compute machines in your cluster, you take responsibility for all operating system life cycle management and maintenance, including performing system updates, applying patches, and completing all other required tasks. Use of Fedora 7 compute machines is deprecated and has been removed in OKD 4.10 and later.

If an instance type for your platform meets the minimum requirements for cluster machines, it is supported to use in OKD.

Additional resources

Requirements for encrypting virtual machines

You can encrypt your virtual machines prior to installing OKD 4 by meeting the following requirements.

When you deploy the OVF template in the section titled "Installing RHCOS and starting the OpenShift Container Platform bootstrap process", select the option to "Encrypt this virtual machine" when you are selecting storage for the OVF template. After completing cluster installation, create a storage class that uses the encryption storage policy you used to encrypt the virtual machines.

Certificate signing requests management

Because your cluster has limited access to automatic machine management when you use infrastructure that you provision, you must provide a mechanism for approving cluster certificate signing requests (CSRs) after installation. The kube-controller-manager only approves the kubelet client CSRs. The machine-approver cannot guarantee the validity of a serving certificate that is requested by using kubelet credentials because it cannot confirm that the correct machine issued the request. You must determine and implement a method of verifying the validity of the kubelet serving certificate requests and approving them.

Networking requirements for user-provisioned infrastructure

All the Fedora CoreOS (FCOS) machines require networking to be configured in initramfs during boot to fetch their Ignition config files.

During the initial boot, the machines require an IP address configuration that is set either through a DHCP server or statically by providing the required boot options. After a network connection is established, the machines download their Ignition config files from an HTTP or HTTPS server. The Ignition config files are then used to set the exact state of each machine. The Machine Config Operator completes more changes to the machines, such as the application of new certificates or keys, after installation.

It is recommended to use a DHCP server for long-term management of the cluster machines. Ensure that the DHCP server is configured to provide persistent IP addresses, DNS server information, and hostnames to the cluster machines.

If a DHCP service is not available for your user-provisioned infrastructure, you can instead provide the IP networking configuration and the address of the DNS server to the nodes at FCOS install time. These can be passed as boot arguments if you are installing from an ISO image. See the Installing FCOS and starting the OKD bootstrap process section for more information about static IP provisioning and advanced networking options.

The Kubernetes API server must be able to resolve the node names of the cluster machines. If the API servers and worker nodes are in different zones, you can configure a default DNS search zone to allow the API server to resolve the node names. Another supported approach is to always refer to hosts by their fully-qualified domain names in both the node objects and all DNS requests.

Setting the cluster node hostnames through DHCP

On Fedora CoreOS (FCOS) machines, the hostname is set through NetworkManager. By default, the machines obtain their hostname through DHCP. If the hostname is not provided by DHCP, set statically through kernel arguments, or another method, it is obtained through a reverse DNS lookup. Reverse DNS lookup occurs after the network has been initialized on a node and can take time to resolve. Other system services can start prior to this and detect the hostname as localhost or similar. You can avoid this by using DHCP to provide the hostname for each cluster node.

Additionally, setting the hostnames through DHCP can bypass any manual DNS record name configuration errors in environments that have a DNS split-horizon implementation.

Network connectivity requirements

You must configure the network connectivity between machines to allow OKD cluster components to communicate. Each machine must be able to resolve the hostnames of all other machines in the cluster.

This section provides details about the ports that are required.

In connected OKD environments, all nodes are required to have internet access to pull images for platform containers and provide telemetry data to Red Hat.

Table 6. Ports used for all-machine to all-machine communications
Protocol Port Description

ICMP

N/A

Network reachability tests

TCP

1936

Metrics

9000-9999

Host level services, including the node exporter on ports 9100-9101 and the Cluster Version Operator on port 9099.

10250-10259

The default ports that Kubernetes reserves

UDP

4789

VXLAN

6081

Geneve

9000-9999

Host level services, including the node exporter on ports 9100-9101.

500

IPsec IKE packets

4500

IPsec NAT-T packets

TCP/UDP

30000-32767

Kubernetes node port

ESP

N/A

IPsec Encapsulating Security Payload (ESP)

Table 7. Ports used for all-machine to control plane communications
Protocol Port Description

TCP

6443

Kubernetes API

Table 8. Ports used for control plane machine to control plane machine communications
Protocol Port Description

TCP

2379-2380

etcd server and peer ports

Ethernet adaptor hardware address requirements

When provisioning VMs for the cluster, the ethernet interfaces configured for each VM must use a MAC address from the VMware Organizationally Unique Identifier (OUI) allocation ranges:

  • 00:05:69:00:00:00 to 00:05:69:FF:FF:FF

  • 00:0c:29:00:00:00 to 00:0c:29:FF:FF:FF

  • 00:1c:14:00:00:00 to 00:1c:14:FF:FF:FF

  • 00:50:56:00:00:00 to 00:50:56:3F:FF:FF

If a MAC address outside the VMware OUI is used, the cluster installation will not succeed.

NTP configuration for user-provisioned infrastructure

OKD clusters are configured to use a public Network Time Protocol (NTP) server by default. If you want to use a local enterprise NTP server, or if your cluster is being deployed in a disconnected network, you can configure the cluster to use a specific time server. For more information, see the documentation for Configuring chrony time service.

If a DHCP server provides NTP server information, the chrony time service on the Fedora CoreOS (FCOS) machines read the information and can sync the clock with the NTP servers.

Additional resources

User-provisioned DNS requirements

In OKD deployments, DNS name resolution is required for the following components:

  • The Kubernetes API

  • The OKD application wildcard

  • The bootstrap, control plane, and compute machines

Reverse DNS resolution is also required for the Kubernetes API, the bootstrap machine, the control plane machines, and the compute machines.

DNS A/AAAA or CNAME records are used for name resolution and PTR records are used for reverse name resolution. The reverse records are important because Fedora CoreOS (FCOS) uses the reverse records to set the hostnames for all the nodes, unless the hostnames are provided by DHCP. Additionally, the reverse records are used to generate the certificate signing requests (CSR) that OKD needs to operate.

It is recommended to use a DHCP server to provide the hostnames to each cluster node. See the DHCP recommendations for user-provisioned infrastructure section for more information.

The following DNS records are required for a user-provisioned OKD cluster and they must be in place before installation. In each record, <cluster_name> is the cluster name and <base_domain> is the base domain that you specify in the install-config.yaml file. A complete DNS record takes the form: <component>.<cluster_name>.<base_domain>..

Table 9. Required DNS records
Component Record Description

Kubernetes API

api.<cluster_name>.<base_domain>.

A DNS A/AAAA or CNAME record, and a DNS PTR record, to identify the API load balancer. These records must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

api-int.<cluster_name>.<base_domain>.

A DNS A/AAAA or CNAME record, and a DNS PTR record, to internally identify the API load balancer. These records must be resolvable from all the nodes within the cluster.

The API server must be able to resolve the worker nodes by the hostnames that are recorded in Kubernetes. If the API server cannot resolve the node names, then proxied API calls can fail, and you cannot retrieve logs from pods.

Routes

*.apps.<cluster_name>.<base_domain>.

A wildcard DNS A/AAAA or CNAME record that refers to the application ingress load balancer. The application ingress load balancer targets the machines that run the Ingress Controller pods. The Ingress Controller pods run on the compute machines by default. These records must be resolvable by both clients external to the cluster and from all the nodes within the cluster.

For example, console-openshift-console.apps.<cluster_name>.<base_domain> is used as a wildcard route to the OKD console.

Bootstrap machine

bootstrap.<cluster_name>.<base_domain>.

A DNS A/AAAA or CNAME record, and a DNS PTR record, to identify the bootstrap machine. These records must be resolvable by the nodes within the cluster.

Control plane machines

<control_plane><n>.<cluster_name>.<base_domain>.

DNS A/AAAA or CNAME records and DNS PTR records to identify each machine for the control plane nodes. These records must be resolvable by the nodes within the cluster.

Compute machines

<compute><n>.<cluster_name>.<base_domain>.

DNS A/AAAA or CNAME records and DNS PTR records to identify each machine for the worker nodes. These records must be resolvable by the nodes within the cluster.

In OKD 4.4 and later, you do not need to specify etcd host and SRV records in your DNS configuration.

You can use the dig command to verify name and reverse name resolution. See the section on Validating DNS resolution for user-provisioned infrastructure for detailed validation steps.

Example DNS configuration for user-provisioned clusters

This section provides A and PTR record configuration samples that meet the DNS requirements for deploying OKD on user-provisioned infrastructure. The samples are not meant to provide advice for choosing one DNS solution over another.

In the examples, the cluster name is ocp4 and the base domain is example.com.

Example DNS A record configuration for a user-provisioned cluster

The following example is a BIND zone file that shows sample A records for name resolution in a user-provisioned cluster.

Sample DNS zone database
$TTL 1W
@	IN	SOA	ns1.example.com.	root (
			2019070700	; serial
			3H		; refresh (3 hours)
			30M		; retry (30 minutes)
			2W		; expiry (2 weeks)
			1W )		; minimum (1 week)
	IN	NS	ns1.example.com.
	IN	MX 10	smtp.example.com.
;
;
ns1.example.com.		IN	A	192.168.1.5
smtp.example.com.		IN	A	192.168.1.5
;
helper.example.com.		IN	A	192.168.1.5
helper.ocp4.example.com.	IN	A	192.168.1.5
;
api.ocp4.example.com.		IN	A	192.168.1.5 (1)
api-int.ocp4.example.com.	IN	A	192.168.1.5 (2)
;
*.apps.ocp4.example.com.	IN	A	192.168.1.5 (3)
;
bootstrap.ocp4.example.com.	IN	A	192.168.1.96 (4)
;
control-plane0.ocp4.example.com.	IN	A	192.168.1.97 (5)
control-plane1.ocp4.example.com.	IN	A	192.168.1.98 (5)
control-plane2.ocp4.example.com.	IN	A	192.168.1.99 (5)
;
compute0.ocp4.example.com.	IN	A	192.168.1.11 (6)
compute1.ocp4.example.com.	IN	A	192.168.1.7 (6)
;
;EOF
1 Provides name resolution for the Kubernetes API. The record refers to the IP address of the API load balancer.
2 Provides name resolution for the Kubernetes API. The record refers to the IP address of the API load balancer and is used for internal cluster communications.
3 Provides name resolution for the wildcard routes. The record refers to the IP address of the application ingress load balancer. The application ingress load balancer targets the machines that run the Ingress Controller pods. The Ingress Controller pods run on the compute machines by default.

In the example, the same load balancer is used for the Kubernetes API and application ingress traffic. In production scenarios, you can deploy the API and application ingress load balancers separately so that you can scale the load balancer infrastructure for each in isolation.

4 Provides name resolution for the bootstrap machine.
5 Provides name resolution for the control plane machines.
6 Provides name resolution for the compute machines.
Example DNS PTR record configuration for a user-provisioned cluster

The following example BIND zone file shows sample PTR records for reverse name resolution in a user-provisioned cluster.

Sample DNS zone database for reverse records
$TTL 1W
@	IN	SOA	ns1.example.com.	root (
			2019070700	; serial
			3H		; refresh (3 hours)
			30M		; retry (30 minutes)
			2W		; expiry (2 weeks)
			1W )		; minimum (1 week)
	IN	NS	ns1.example.com.
;
5.1.168.192.in-addr.arpa.	IN	PTR	api.ocp4.example.com. (1)
5.1.168.192.in-addr.arpa.	IN	PTR	api-int.ocp4.example.com. (2)
;
96.1.168.192.in-addr.arpa.	IN	PTR	bootstrap.ocp4.example.com. (3)
;
97.1.168.192.in-addr.arpa.	IN	PTR	control-plane0.ocp4.example.com. (4)
98.1.168.192.in-addr.arpa.	IN	PTR	control-plane1.ocp4.example.com. (4)
99.1.168.192.in-addr.arpa.	IN	PTR	control-plane2.ocp4.example.com. (4)
;
11.1.168.192.in-addr.arpa.	IN	PTR	compute0.ocp4.example.com. (5)
7.1.168.192.in-addr.arpa.	IN	PTR	compute1.ocp4.example.com. (5)
;
;EOF
1 Provides reverse DNS resolution for the Kubernetes API. The PTR record refers to the record name of the API load balancer.
2 Provides reverse DNS resolution for the Kubernetes API. The PTR record refers to the record name of the API load balancer and is used for internal cluster communications.
3 Provides reverse DNS resolution for the bootstrap machine.
4 Provides reverse DNS resolution for the control plane machines.
5 Provides reverse DNS resolution for the compute machines.

A PTR record is not required for the OKD application wildcard.

Load balancing requirements for user-provisioned infrastructure

Before you install OKD, you must provision the API and application Ingress load balancing infrastructure. In production scenarios, you can deploy the API and application Ingress load balancers separately so that you can scale the load balancer infrastructure for each in isolation.

If you want to deploy the API and application Ingress load balancers with a Fedora instance, you must purchase the Fedora subscription separately.

The load balancing infrastructure must meet the following requirements:

  1. API load balancer: Provides a common endpoint for users, both human and machine, to interact with and configure the platform. Configure the following conditions:

    • Layer 4 load balancing only. This can be referred to as Raw TCP or SSL Passthrough mode.

    • A stateless load balancing algorithm. The options vary based on the load balancer implementation.

    Do not configure session persistence for an API load balancer. Configuring session persistence for a Kubernetes API server might cause performance issues from excess application traffic for your OKD cluster and the Kubernetes API that runs inside the cluster.

    Configure the following ports on both the front and back of the load balancers:

    Table 10. API load balancer
    Port Back-end machines (pool members) Internal External Description

    6443

    Bootstrap and control plane. You remove the bootstrap machine from the load balancer after the bootstrap machine initializes the cluster control plane. You must configure the /readyz endpoint for the API server health check probe.

    X

    X

    Kubernetes API server

    22623

    Bootstrap and control plane. You remove the bootstrap machine from the load balancer after the bootstrap machine initializes the cluster control plane.

    X

    Machine config server

    The load balancer must be configured to take a maximum of 30 seconds from the time the API server turns off the /readyz endpoint to the removal of the API server instance from the pool. Within the time frame after /readyz returns an error or becomes healthy, the endpoint must have been removed or added. Probing every 5 or 10 seconds, with two successful requests to become healthy and three to become unhealthy, are well-tested values.

  2. Application Ingress load balancer: Provides an ingress point for application traffic flowing in from outside the cluster. A working configuration for the Ingress router is required for an OKD cluster.

    Configure the following conditions:

    • Layer 4 load balancing only. This can be referred to as Raw TCP or SSL Passthrough mode.

    • A connection-based or session-based persistence is recommended, based on the options available and types of applications that will be hosted on the platform.

    If the true IP address of the client can be seen by the application Ingress load balancer, enabling source IP-based session persistence can improve performance for applications that use end-to-end TLS encryption.

    Configure the following ports on both the front and back of the load balancers:

    Table 11. Application Ingress load balancer
    Port Back-end machines (pool members) Internal External Description

    443

    The machines that run the Ingress Controller pods, compute, or worker, by default.

    X

    X

    HTTPS traffic

    80

    The machines that run the Ingress Controller pods, compute, or worker, by default.

    X

    X

    HTTP traffic

    If you are deploying a three-node cluster with zero compute nodes, the Ingress Controller pods run on the control plane nodes. In three-node cluster deployments, you must configure your application Ingress load balancer to route HTTP and HTTPS traffic to the control plane nodes.

Example load balancer configuration for user-provisioned clusters

This section provides an example API and application Ingress load balancer configuration that meets the load balancing requirements for user-provisioned clusters. The sample is an /etc/haproxy/haproxy.cfg configuration for an HAProxy load balancer. The example is not meant to provide advice for choosing one load balancing solution over another.

In the example, the same load balancer is used for the Kubernetes API and application ingress traffic. In production scenarios, you can deploy the API and application ingress load balancers separately so that you can scale the load balancer infrastructure for each in isolation.

If you are using HAProxy as a load balancer and SELinux is set to enforcing, you must ensure that the HAProxy service can bind to the configured TCP port by running setsebool -P haproxy_connect_any=1.

Sample API and application Ingress load balancer configuration
global
  log         127.0.0.1 local2
  pidfile     /var/run/haproxy.pid
  maxconn     4000
  daemon
defaults
  mode                    http
  log                     global
  option                  dontlognull
  option http-server-close
  option                  redispatch
  retries                 3
  timeout http-request    10s
  timeout queue           1m
  timeout connect         10s
  timeout client          1m
  timeout server          1m
  timeout http-keep-alive 10s
  timeout check           10s
  maxconn                 3000
listen api-server-6443 (1)
  bind *:6443
  mode tcp
  option  httpchk GET /readyz HTTP/1.0
  option  log-health-checks
  balance roundrobin
  server bootstrap bootstrap.ocp4.example.com:6443 verify none check check-ssl inter 10s fall 2 rise 3 backup (2)
  server master0 master0.ocp4.example.com:6443 weight 1 verify none check check-ssl inter 10s fall 2 rise 3
  server master1 master1.ocp4.example.com:6443 weight 1 verify none check check-ssl inter 10s fall 2 rise 3
  server master2 master2.ocp4.example.com:6443 weight 1 verify none check check-ssl inter 10s fall 2 rise 3
listen machine-config-server-22623 (3)
  bind *:22623
  mode tcp
  server bootstrap bootstrap.ocp4.example.com:22623 check inter 1s backup (2)
  server master0 master0.ocp4.example.com:22623 check inter 1s
  server master1 master1.ocp4.example.com:22623 check inter 1s
  server master2 master2.ocp4.example.com:22623 check inter 1s
listen ingress-router-443 (4)
  bind *:443
  mode tcp
  balance source
  server compute0 compute0.ocp4.example.com:443 check inter 1s
  server compute1 compute1.ocp4.example.com:443 check inter 1s
listen ingress-router-80 (5)
  bind *:80
  mode tcp
  balance source
  server compute0 compute0.ocp4.example.com:80 check inter 1s
  server compute1 compute1.ocp4.example.com:80 check inter 1s
1 Port 6443 handles the Kubernetes API traffic and points to the control plane machines.
2 The bootstrap entries must be in place before the OKD cluster installation and they must be removed after the bootstrap process is complete.
3 Port 22623 handles the machine config server traffic and points to the control plane machines.
4 Port 443 handles the HTTPS traffic and points to the machines that run the Ingress Controller pods. The Ingress Controller pods run on the compute machines by default.
5 Port 80 handles the HTTP traffic and points to the machines that run the Ingress Controller pods. The Ingress Controller pods run on the compute machines by default.

If you are deploying a three-node cluster with zero compute nodes, the Ingress Controller pods run on the control plane nodes. In three-node cluster deployments, you must configure your application Ingress load balancer to route HTTP and HTTPS traffic to the control plane nodes.

If you are using HAProxy as a load balancer, you can check that the haproxy process is listening on ports 6443, 22623, 443, and 80 by running netstat -nltupe on the HAProxy node.